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The electronic structure and magnetism in fayalites M2SiO4 (M=Fe and Co) have been studied by density functional theory within the generalized gradient approximation with the on-site Coulomb energy taken into account (GGA+U). Stable insulating antiferromagnetic solutions are obtained. It is found that the gap opening in these fayalites results mainly from strong on-site Coulomb interactions of the magnetic atoms. In the band structures, the conduction bands originate mainly from the M(3d) orbitals of M2SiO4. The top of valence bands consists of the Fe (3d) orbitals in Fe2SiO4, and of the Co(3d)–O(2p) hybridization in Co2SiO4. All calculated orbital magnetic moments are very small. [Copyright &y& Elsevier]

First-principles density functional calculations of the total energy, magnetic moments and magnetocrystalline anisotropy energy (MAE) of CrO2 as a function of both volume and uniaxial strain along the c-axis have been performed. The highly accurate all-electron full-potential linearized augmented plane wave method and the generalized gradient approximation to the exchange–correlation potential are used. The calculated structural properties (lattice constants and unit cell volume) are in excellent agreement with experiments (with 0.5%). The calculated bulk and Young’s modulii are 2.56 and 2.02 Mbar, respectively. The calculated MAE increases almost linearly with the uniaxial strain and remains positive in the strain range of -4–4%. Thus, the calculations predict that the easy magnetization axis is along the c-axis, in agreement with experiments. However, the calculated anisotropy constant is about six times larger than the measured value. The calculated magnetoelastic coupling constant is 1.2×107 erg/cm3 and the magnetostriction coefficient λ001 is -2.59×10-5. [Copyright &y& Elsevier]

We haved calculated the magnetic moments and magnetic anisotropy energy (MAE) of the ordered Fe0.5Pd0.5 alloy by using relativistic linear muffin-tin orbital and full-potential linear augmented plane wave methods and also including the orbital polarization correction (OPC) and the generalized gradiant approximation. The OPC substantially increases the Fe orbital moments in the alloy, thereby reducing the discrepancy between the measured and theoretical orbital moments. For all the lattice parameters considered, the [0 0 1] direction is found to be the easy axis, thus showing no spin-reorientation transition as suggested recently. The calculated MAE agrees with experiments. [Copyright &y& Elsevier]

The magnetic proximity effect (MPE) has recently been explored to manipulate interfacial properties of two-dimensional (2D) transition metal dichalcogenide (TMD)/ferromagnet heterostructures for use in spintronics and valleytronics. However, a full understanding of the MPE and its temperature and magnetic field evolution in these systems is lacking. In this study, the MPE has been probed in Pt/WS2/BPIO (biphase iron oxide, Fe3O4 and α-Fe2O3) heterostructures through a comprehensive investigation of their magnetic and transport properties using magnetometry, four-probe resistivity, and anomalous Hall effect (AHE) measurements. Density functional theory (DFT) calculations are performed to complement the experimental findings. We found that the presence of monolayer WS2 flakes reduces the magnetization of BPIO and hence the total magnetization of Pt/WS2/BPIO at T > ~120 K—the Verwey transition temperature of Fe3O4 (TV). However, an enhanced magnetization is achieved at T < TV. In the latter case, a comparative analysis of the transport properties of Pt/WS2/BPIO and Pt/BPIO from AHE measurements reveals ferromagnetic coupling at the WS2/BPIO interface. Our study forms the foundation for understanding MPE-mediated interfacial properties and paves a new pathway for designing 2D TMD/magnet heterostructures for applications in spintronics, opto-spincaloritronics, and valleytronics. [ABSTRACT FROM AUTHOR]

Abstract: The chemical pressure control in (Sr2−x Ca x )FeMoO6 (0⩽ x ⩽2.0) with double perovskite structure has been investigated systematically. We have performed first-principles total energy and electronic structure calculations for x =0 and x =2.0. The increasing Ca content in (Sr2−x Ca x )FeMoO6 samples increases the magnetic moment close to the theoretical value due to reduction of Fe/Mo anti-site disorder. An increasing Ca content results in increasing (Fe2+ +Mo6+)/(Fe3+ +Mo5+) band overlap rather than bandwidth changes. This is explained from simple ionic size arguments and is supported by X-ray absorption near edge structure (XANES) spectra and band structure calculations. [Copyright &y& Elsevier]

We study the magnetic properties of platinum diselenide (PtSe2) intercalated with Ti, V, Cr, and Mn, using first-principle density functional theory (DFT) calculations and Monte Carlo (MC) simulations. First, we present the equilibrium position of intercalants in PtSe 2 obtained from the DFT calculations. Next, we present the magnetic groundstates for each of the intercalants in PtSe 2 along with their critical temperature. We show that Ti intercalants result in an in-plane AFM and out-of-plane FM groundstate, whereas Mn intercalant results in in-plane FM and out-of-plane AFM. V intercalants result in an FM groundstate both in the in-plane and the out-of-plane direction, whereas Cr results in an AFM groundstate both in the in-plane and the out-of-plane direction. We find a critical temperature of <0.01 K, 111 K, 133 K, and 68 K for Ti, V, Cr, and Mn intercalants at a 7.5% intercalation, respectively. In the presence of Pt vacancies, we obtain critical temperatures of 63 K, 32 K, 221 K, and 45 K for Ti, V, Cr, and Mn-intercalated PtSe 2 , respectively. We show that Pt vacancies can change the magnetic groundstate as well as the critical temperature of intercalated PtSe 2 , suggesting that the magnetic groundstate in intercalated PtSe 2 can be controlled via defect engineering. [ABSTRACT FROM AUTHOR]

Here, we present a novel approach to controlling magnetic interactions between atomic-scale nanowires. Our ab initio calculations demonstrate the possibility to tune magnetic properties of Fe nanowires formed on vicinal Cu surfaces. Both intrawire and interwire magnetic exchange parameters are extracted from density functional theory (DFT) calculations. This study suggests that the effective interwire magnetic exchange parameters exhibit Ruderman–Kittel–Kasuya–Yosida-like (RKKY) oscillations as a function of Fe interwire separation. The choice of the vicinal Cu surface offers possibilities for controlling the magnetic coupling. Furthermore, an anisotropic Heisenberg model was used in Monte Carlo simulations to examine the stability of these magnetic configurations at finite temperatures. The predicted critical temperatures of the Fe nanowires on Cu(422) and Cu(533) surfaces are well above room temperature. [ABSTRACT FROM AUTHOR]